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Ultraviolet light and leaf emission of NOx

Subjects

Abstract

Nitrogen oxides are trace gases that critically affect atmospheric chemistry and aerosol formation1. Vegetation is usually regarded as a sink for these gases, although nitric oxide and nitrogen dioxide have been detected as natural emissions from plants2,3. Here we use in situ measurements to show that solar ultraviolet radiation induces the emission of nitrogen oxide radicals (NOx) from Scots pine (Pinus sylvestris) shoots when ambient concentrations drop below one part per billion. Although this contribution is insignificant on a local scale, our findings suggest that global NOx emissions from boreal coniferous forests may be comparable to those produced by worldwide industrial and traffic sources.